1. Field of the Invention
The present invention relates to a fixed capacity swash plate type compressor that has a fixed refrigerant discharge capacity, and a manufacturing method for the same.
2. Description of the Related Art
There are two types of conventional swash plate type compressors used with automotive air conditioners. In one type, the tilt angle or inclination of the swash plate with respect to a drive shaft is fixed so as to fix the discharge capacity of a refrigerant. The other is a variable capacity type in which the inclination of the swash plate with respect to the drive shaft is changed to so that the discharge capacity of the refrigerant may be changed.
The foregoing conventional fixed capacity swash plate type compressor has a simpler structure than the variable capacity swash plate type compressor, thus having the advantage of a lower cost. The fixed capacity type, however, has a problem in that it has great pressure fluctuations at startup i.e., a large startup shock because the pistons therein always operate at full stroke. The fixed capacity type also has a problem in that frequent switching ON/OFF of an electromagnetic clutch causes shock because the refrigerating capacity is adjusted by turning the electromagnetic clutch ON/OFF.
On the other hand, variable capacity swash plate type compressors are operated with the swash plate thereof set at a minimum inclination at startup, so that startup shocks such as those taking place in the fixed capacity swash plate type compressor are suppressed. Further, the variable capacity type does not require that the electromagnetic clutch be turned ON/OFF frequently because the inclination of the swash plate is adjusted in accordance with refrigeration load to control the capacity; therefore, it provides higher operating efficiency and is superior in terms of comfort. The variable capacity type, however, incorporates a hinge mechanism for changing the inclination of the swash plate according to crank chamber pressure and is constructed so as to control the crank chamber pressure arising from changes in a suction pressure with a capacity control valve assembly installed in the housing assembly. This has a drawback in that the structure becomes more complicated with more components and the use of the expensive capacity control valve assembly leads to higher cost.
Thus, both types of swash plate compressors have their advantages and disadvantages, so that they need to be chosen properly according to individual applications. However, there are a considerable number of components that have not been standardized even for compressors having the same capacity because of the structural difference in which the inclination of the swash plate is either fixed or made variable. This has been adversely affecting efforts for achieving economies of mass production and has been responsible for increased cost.
As a solution to the problem discussed above, there has been disclosed, in Japanese Patent Application Laid-open No. 9-228948, a fixed capacity swash plate type compressor intended for standardized components. This conventional known fixed capacity swash plate type compressor is fabricated by replacing a rear housing provided with a capacity control valve assembly in a variable capacity swash plate type compressor with a rear housing that is not provided with the capacity control valve assembly. Hence, the standardization of components between these two compressors is not yet very satisfactory. In addition, the structural modification requires that the assembly procedure or assembly process of the variable capacity swash plate type compressor be significantly changed. Thus, further improvements in productivity has been demanded.